Dual boot your hard drive should not affect your warranty...
Hybrid hard drives may be confused more as their tiny SSD's is optimized for one operating system.
be careful when installing your dual boot to NOT overwrite your rescue partition.
if you know what your are doing, you can install RAM yourself. It's critical you don't short out an component or damage the RAM sockets.
to clarify.... what computer is this? Some machines may have RAM limitations. Some machines have the RAM SOLDERED on so they are not removeable. Some computers may have hybrid SSD's.
